1. Field of the Invention
The present invention relates to a catalyst for preparing hydrocarbons by hydrogenation of carbon dioxide and more particularly, the Fe—Cu—K/γ—Al2O catalyst prepared by impregnation which enables producing hydrocarbons in high yield for more than 2000 hours due to its excellent activity and stability.
2. Description of Related Art
Carbon dioxide is one of the so-called greenhouse gases. It is known that it absorbs infrared energy and prevents such energy from leaving the atmosphere. Accumulation of carbon dioxide in the atmosphere caused by a huge amount of the fossil and organic-based fuel consumption may therefore contribute to an increase in average global temperatures, resulting in more frequent and more violent natural catastrophes (e.g., periods of drought, flood, storm). However, the world's growing population and increasingly technological society have made it difficult for the world's energy and material resources to keep pace with the current trends. Therefore, increased efforts are required to conserve the environment by restricting the use of fossil and organic-based fuel. To activate this, recycling of carbon dioxide into useful hydrocarbons would help to alleviate the problem of our diminishing hydrocarbon resources.
In order to convert carbon dioxide to useful hydrocarbons, the inventors have disclosed a process for preparing hydrocarbons over a Fe—K/γ—Al3O3 catalyst performed by flowing gas mixture (H2/CO2=1.0˜5.0 v/v) into the reactor at 200˜500° C., 1˜100 atm and 500˜20,000 h−1 of the space velocity (U.S. Pat. No. 5,952,540). A catalyst used in this process is pretreated Fe—K/γ—Al2O3 by reduction and activation, contains 5˜50 wt. % of Fe to total catalyst weight and includes 0.1˜1.5 of atomic ratio of K/Fe. However, when Fe—K/γ—Al2O3 catalyst has been used for more than 800 hours, the conversion rate of carbon dioxide to hydrocarbons is decreased by more than 10% and productivity of hydrocarbons is also decreased by more than 20%. On top of that, formation of undesirable carbon monoxide and methane gas are extremely increased by 70% and 30%, respectively.